Navigating the Digital Frontier: Transforming Endodontic Diagnosis through Digitization. Part 2

Dual wave spectrophotometry (DWS)

In DWS, the contents of the pulp chamber are determined using dual-wavelength visible light. The use of visible light minimizes the effects caused by other sources, such as laser beams. It measures oxygen saturation within the blood vessels rather than blood flow, and therefore does not depend on pulsatile blood flow (Figure 1). The machines are portable, inexpensive, accurate and their use is non-invasive.¹ Nissan et al conducted an in vitro investigation to determine whether DWS was capable of detecting teeth with empty pulp chambers filled with fixed pulp tissue or oxygenated blood, and they concluded that continuous-wave spectrophotometry might be useful in determining pulpal status.² However, this requires further research for its clinical use in dentistry.

Photoplethysmography

Photoplethysmography is a non-invasive optical measurement technique used to measure the pulsatile variation in the blood supply of the pulp.¹ The plethysmography recordings are based on transmitted light, which is affected by the oxygen saturation of the blood flow. Arterial vasoconstriction will result in reduced light transmission, which shows as an upwards shift in baseline and increase in pulse wave amplitude on the photoplethysmogram (Figure 2).³

Micro-CT

High-resolution CTs, including micro-CTs, have revolutionized dental research in several domains, such as evaluating surrounding bone and implants, endodontic studies on osteological changes and root resorption caused by bacterial infection at the apical area, scientific studies analyzing the interfaces between tooth restoration and natural teeth, and craniofacial bone growth and development. Despite not being appropriate for clinical use, micro-CT has developed over the past decade, providing a non-invasive, repeatable, and precise method for qualitative and quantitative assessment of teeth and materials.⁴ It is an effective tool for preclinical and experimental research, but its clinical feasibility requires further research (Figure 3).

Optical coherence tomography (OCT)

In OCT, the concept of ultrasound is combined with the imaging capabilities of a microscope (Figure 4).⁵ OCT employs infrared light waves to ascertain the internal microstructure within the oral biological tissues, while ultrasonography creates pictures from backscattered echoes. In dentistry, OCT shows potential to be used in the early diagnosis and detection of demineralization, remineralization, restorative failure, canal anatomy, calcification, enamel cracks, vertical root fractuers, canal transportation, pre-cancerous lesions and periodontal diseases.

Endoscopic, polarization-sensitive, doppler, and high-resolution are all different types of OCT.⁶ Endoscopic OCT currently requires suitable tips to be used, and no clinical studies or devices are available.⁷ Clinically, OCT is a non-invasive and non-destructive procedure, generates microscopic images without the use of ionizing radiation, and does not require a dry canal for visualization. However, there are limitations to its use, one being an insufficient scanning range of only a few millimetres and as such, a lesion scan may require a very large number of pictures. A potential solution is the development of a dental probe that can scan the entire lesion and focus on specific areas rapidly. Secondly, the low penetration depth restricts its clinical use. This problem could be solved by using a high-quality light source, but which would increase the cost of the system.⁸

Magnetic resonance imaging (MRI)

MRI is a non-invasive, non-destructive imaging technology that enables accurate viewing of the pulp and surrounding tissues without the use of ionizing radiation.⁹ MRI is used for the diagnosis of soft tissue disease in the salivary glands, tumours, ligament tears, and malignancies to assess the temporomandibular joint (TMJ) and visualize brain and spinal cord damage. MRI may provide significant information on tissues, assisting clinicians in the diagnosis and treatment planning of peri-apical diseases, as well as determining pulp viability.¹⁰ Traditional MRI techniques can visualize and yield scans of soft tissue, pulp, and connected periodontal membranes, making them a tool of choice during root canal therapy, but they are time-consuming, making them unsuitable for clinical application. Considering the high acquisition cost and long scan time. The benefits of MRI need to be weighed to justify its use in endodontics. MRI has high soft tissue contrast, which helps in the evaluation of various tissue components, and it helps in diagnosing a cystic lesion more accurately than a granulomatous lesion.¹⁰ In the case of regenerative endodontics, it helps to evaluate the reperfusion of canals. However, considering that MRI can not be used to visualize hard tissues, such as enamel and dentine, makes it an impractical tool in endodontics.¹¹ MRI has a promising future in dentistry. It is biologically safe and does not you ionizing radiation.

Artificial intelligence (AI)

AI uses computer technology for critical analysis and decision making.¹² Clinical diagnosis and imaging interpretations are subjective and do vary among clinicians. AI could help to maintain uniformity in diagnosis and therefore improve long-term treatment outcomes. The use of AI algorithms trained to identify peri-apical lesions from radiographs and CBCT scans can enhance diagnostic accuracy and reliability. It assists physicians in achieving detection accuracy comparable to, or better than, that of previously experienced specialists.^13,14 Endres et al compared the ability of oral maxillofacial surgeons to detect peri-apical radiolucencies in panoramic radiographs with a deep learning model trained on a curated set of radiographic images and concluded that AI could match up the diagnostic accuracy of 24 oral maxillofacial surgeons.¹⁵

According to a systematic review, CBCT performed better in identifying vertical root fractures (VRF) in unfilled canals than in filled canal.¹⁶ The diagnosis of VRF has always posed a diagnostic dilemma for clinicians.¹⁷ Promising results have been demonstrated when applying AI with the convolutional neuron network (CNN) approach to detect canal configurations using CBCT and panoramic radiographs. AI has shown promising results in detecting VRF using CBCT imaging by using the CNN and probabilistic neuron network (PNN).¹⁸ Lahoud et al evaluated CBCT images and concluded that AI performed accurately and faster than its human counterpart.¹⁹ Leite et al studied panoramic images with AI and showed higher sensitivity and specificity.²⁰

Dynamic navigation system (DNS)

DNS can identify the 3D position of important structures using a stereoscopic camera, with or without infrared light, and a computer set up with a dynamic navigation system that provides real-time feedback to clinicians regarding the drill path that can be created using the CBCT images. It is a computer-aided technology to determine the entry point and virtually plan the 3D path for procedures. DNS continuously monitors the position of the dental drill and patient during surgery using motion tracking technology (Figure 5).²¹ This helps in the accurate detection of canals and the planning of minimally invasive endodontic access in cases of calcified, obliterated or sclerosed canals. It can aid in endodontic microsurgeries for accurate localization of root apex, apicectomy, and minimally invasive bone removal to prevent iatrogenic errors, particularly in cases of post removal and re-treatment to prevent perforation.²²

Metaverse in endodontics

A metaverse is a virtual world that uses a similar replica of the biological structures of the stomatognathic system. A metaverse could provide access to higher learning opportunities through dental lectures, courses and dental telehealth conversations with people participating as virtual avatars.^23,24 Mirror images of various procedures and surgeries can be mimicked for practice for the dentist. Fearful and apprehensive patients can visualize and receive virtual treatment, interact and consult the staff and watch oral hygiene videos in the dental metaverse.

Bueno et al investigated CBCT modelling methods for root canal endoscopy. Endoscopy was suggested to visualize explore inside the root canal as well as visualize the shape and anatomical microstructures, ramification, and apical foramen using a pulp cavity filter and internal scanning where the dentin density is transparent to allow visualization of the pulp cavity.²⁵